Low voltage hot knife



y 7 47- P. KREBS 2,421,125

LOW VOLTAGE HOT KNIFE Filed March 16, 1945 INVENTOR. PAUL KREBS WM 7% We;

ATTORNEY Patented May 27, 1947 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to hot knives adapted to be used for uncapping honeycombs. It may also be used in industries, wherein any heated knife may be employed such as in the butcher business, bakeries, for cutting tar, fatty solids, and the like.

An object of the invention is to provide a device of the character referred to, which employs a low voltage electric current so that any danger of shock or electrocution of the operator is eliminated.

Another object of the invention is the provision of a device of the character referred to, in which the cutting blade forms the heating element and vice versa.

Another object of the invention is the provision of a device of the character referred to, which is provided with novel means for cooling certain areas thereof, whereby the heat may be rapidly dissipated from the base of the blade so that the handle is prevented from getting unduly warm.

The foregoing and other objects and advantages of the invention will become more apparent as the description proceeds, reference being made from time to time to the accompanying drawings which form a part of the within disclosure, in which drawings:

Fig. 1 is a plan view of a device embodying my invention.

Fig. 2 is a side elevation of the device illustrated in Fig. 1.

Fig. 3 is an end view of the handle of the device illustrated in Fig. 1.

Fig. 4 is a schematic view of the electrical circuits.

Fig. 5 is a plan view of one of the radiators employed in dissipating the heat.

Referring now more particularly to the drawings, it will be understood that in the embodiment herein disclosed, my improved device consists of a cutting blade 1 which may be made of any suitable metal or alloy of metals to provide the electrical resistance required.

The blade 1 may be straight or tapered or may assume any desirable shape or size for the particular purpose for which it is adapted to be used. The blade 1 is provided with a central slot 8 which extends longitudinally throughout substantially the entire length of the blade and provides a suitable air gap between the two resulting sections of the blade.

The bifurcated portion of the blade 1 is mounted in suitable slots 9 formed in the handle [0, the latter being preferably made of non-heat conducting material. The blade 'I is secured to the handle H] by rivets II or other suitable means.

A low voltage heat conductor is connected as at [2 and 13 to each respective section of the blade 1 so that a circuit is completed through the blade I. The conductors I2 and I3 are connected to flexible conductors I 4 and [5 which are in turn connected as at 3 and I9 to the secondary winding 2!] of a suitable transformer 2|, the primary winding 22 of which is connected to high voltage lines 23 and 24, in the circuit of which is positioned a multi-post switch 25, whereby various loads may be introduced to the primary winding 22.

26 indicates a pilot light positioned in the secondary circuit which indicates when the device is in operation.

In order to help cool the handle I!) and maintain a comfortable temperature therein for the operator, I employ a radiator element 21 on each section of the blade 1. The radiators 2'! are channel-shaped copper members which are rivetted as at 28 to the respective sections of the blade 1. Holes 29 may also be positioned in the blade 1 adjacent to the handle I!) to reduce the stock and provide air spaces for further dissipation of the heat in this area.

When the knife is electrically connected to the secondary winding 20 of the transformer 2|, a low voltage current, approximately 1 volts, is permitted to flow through the leads [4 and I5, completing a circuit through the two sections comprising the cutting blade 1. When the knife is cooled, the circuit will draw approximately 136 amperes which will heat the knife to a temperature of approximately 212 Fahrenheit more or less. As the temperature of the knife blade increases, the amperage will be reduced until it reaches the point of approximately 89 amperes when the blade reaches its highest temperature. The temperatures and amperage herein stated, of course, will vary in difierent size blades and with different materials used.

The blade will start to heat first at the point around which area the highest degree of temperature will be maintainend during the heating operation.

The section of the blade adjacent to the handle will normally operate at a slightly lower temperature.

Inasmuch as we are utilizing only approximately 1 volts, the blade may be plunged into water or may be grasped by the hand or may be short-circuited otherwise without danger of shocking the operator or destroying the device.

2,421,125 v V 3 4 a Having described my invention, what I claim REFERENCES CITED and desire to secure by Letters Patent is:

In a device of the character described including a bifurcated blade and a handle, an offset portion The following references are of record in the file of this patent:

in said blade adjacent the handle, low voltage 5 UN E STATES PATENTS leads connected to the respective legs of said blade Number Name Date at said oifset, and a channel member of great 1,834,555 Tittle Dec 1, 1931 h at conductivity across said blade beneath said 2,041,018 Persons May 19, 1936 ffset nd adjacent said handle. 1,849,595 Shaw Man 15, 1932 10 2,016,523 Stringer Oct. 8, 1935 PAUL KREBS. 

